For over 30 years, the popular I.W. Harper bourbon was produced exclusively for overseas markets, in particular Japan. After a long absence, Diageo reintroduced the brand to the US market in 2015. I.W. Harper 15 Years Old is distilled at the New Bernheim Distillery in Louisville and aged in the Stitzel-Weller warehouses. The I.W. Harper brand was introduced in the 1870s by the Bernheim Brothers. The “I.W.” refers to the initials of Isaac Wolfe Bernheim, but a different surname was chosen for marketability.